As the soon-to-be Duke and Duchess share their love story with the world, it's easy to see just how smitten they are with each other.

Throughout every chapter of their romance, the couple continue to throw out the royal rule book. Who could forget when they broke with protocol and PDA-ed all over the place as they strolled hand-in-hand around the Sunken Gardens during their engagement photo call last year?

But what about the other British Royals and their respective marriages?

Now to Love speaks exclusively with Louise Mahler, Leadership Influencer and Body Language expert, (aka the genius woman who perfectly predicted the order of the top three for both The Bachelor Australia and Bachelorette Australia finales) as she weighs in on the key players and reveals some fascinating insights into their relationships…

Prince Harry and Meghan Markle: Crazy in love

Most of their relationship has played out behind closed doors but last year the world was finally gifted with a very generous serving of Prince Harry and Meghan Markle's romance when they announced their engagement.

"Walking out to the cameras, both were looking down expressing overwhelming anxiety but this was contrasted by a strong and determined stride from both of them," she tells us.

"Harry NEVER puts his hand in his jacket, you can tell he's on edge. I think Harry was genuinely nervous with the high breath and uncomfortable eye contact."

Harry nervously put his hand in his pocket but Meghan's warm embrace shows she's trying to calm his jitters.

The couple have a great chemistry and love joking about.

Meghan was quick to put her fiancé at ease, gently rubbing his arm and always keeping him close by her side.

"Meghan held onto Harry, slightly behind him and pulling her hair aside. This is a confident, strong actress and an experienced public performer. You can tell they had thought about this 'performance' as it felt slightly rehearsed," she adds.

The Queen and Prince Philip: They’ve still got it

Seven decades on and the monarch and her man still depend and adore one another.

WATCH: Prince Philip on his wife, The Queen. Post continues...

The Queen's left elbow edges towards her husband, indicating she wants him close by.

"When the Queen is with Prince Philip her face lights up, she smiles and we don't see that in any other part of her life. Her breath is low. Her eyes are bright. Her smile is wide. He relaxes her," Louise points out.

Looking at their anniversary portraits to mark their platinum anniversary Louise notes: "She leans towards him. See her left elbow when he is by her side. It goes towards him, which means she wants to be close."

WATCH: The Queen's sweet tribute to Prince Philip. Post continues...

Prince Charles and Duchess Camilla: The jury is still out

It's the most controversial royal romance in recent history, so what does our body language expert have to say over the state of Prince Charles and Duchess Camilla's marriage?

Well, she's pretty skeptical and it all comes down to Camilla's apparent strained smile.

"Camilla doesn't smile with both her eyes and mouth to make a complete smile. Like Tony Abbott, she does a special line in a mouth-only smile, which is very concerning. Look closely at photos of Prince Charles and Duchess Camilla, they are both faking it to make it. Their eyes are dead," Louise claims.